Small internal combustion engines are used to power a variety of various products such as chain saws, leaf blowers, lawn mowers, edgers, grass and weed trimmers, and the like. Many of these engines are single cylinder two-stroke or four-stroke gasoline powered internal combustion engines having a carburetor or other device with a throttle valve controlling the fuel and air mixture supplied to the operating engine. Many of these products have a manually movable throttle lever or trigger remote from the throttle valve that controls the opening and closing of the throttle valve and in close proximity a kill switch connected to an ignition control module by two terminals and two wires so that closing of the normally open kill switch causes the ignition module to terminate supplying an electric current to a spark plug of the engine and thus stopping operation of the engine. Typically, these engines do not have a separate battery for supplying an electric current to the spark plug and instead utilize a magneto system with magnets mounted on the flywheel to generate power for a capacitive discharge ignition system of the module which typically also varies and controls ignition timing of the current at a high potential voltage supplied to the spark plug. Typically, these engines are manually cranked for starting with an automatic recoil rope starter.
For many engine control systems, it would be desirable to sense when the throttle valve is near or at its wide open throttle (WOT) position for one or more of a variety of purposes including without limitation initiating automatic or self-adjustment of the ratio of fuel-to-air in the mixture, cancelling a centrifugal clutch engagement limiter feature when the operator advances the throttle valve from fast idle or idle to a wide open throttle (WOT) position, initiating active engine acceleration such as by advancing ignition timing and/or fuel enrichment of the fuel-air mixture supplied to the engine, activating engine rapid comedown enhancement from WOT to idle such as by retarding ignition timing and enleaning fuel in the fuel-air mixture, etc.